Risk Assessment Of Urban Road Collapse Geological Disease Based On OCTEM

China’s urban roads are widely faced with the risk of road cave-in.In recent years,road cave-in accidents occur frequently,which pose a great threat to people’s life safety and also bring huge economic losses to the society.The problem of urban road cave-in is deeply concerned by the people and the society.Aiming at this problem,this paper aims at preventing the geological disaster of urban road cavity collapse,and carries out systematic scientific research on the quantitative detection technology of underground cavity of urban road and the cause mechanism of cavity collapse,aiming at establishing a set of geological disaster risk assessment method of urban road cavity collapse.Opposing coils transient electromagnetic method(OCTEM)is an important method in the field of urban underground space detection.To improve the level of urban road hollow quantitative detection technology research,on the basis of 3D vector finite element algorithm,build the antithetic magnetic source,established OCTEM three-dimensional forward modeling algorithm,with H,K type layered model of one dimensional numerical filter solution contrast found that relative error range within 10%,and proved the feasibility of the algorithm.By constructing a three-dimensional geoelectric model of cavities,the relative anomaly deviation between the response with cavities and the background response was used as the influence index to study the OCTEM response characteristics of different types of cavities under different burial depths and different sizes.The OCTEM response characteristics of cavities were further studied by physical simulation and urban road test.Finally through discrete element particle flow analysis software PFC to trap mechanism of urban pavement hollow numerical simulation of the development to reflect the underground cavity from the microscopic view,the failure mechanism of surface subsidence and the quantitative analysis of the size of the hole,buried depth and other parameters on the road settlement rule,the influence of subsidence as the main reference according to the risk classification of the subterranean cavitation,A risk assessment method of urban road collapse geological disease based on OCTEM is established.